Documents were seized in the Manchester searches, which took place 10 days after the IRA put its weapons beyond use and on the day Sinn Fein President Gerry Adams met Prime Minister Tony Blair in Downing Street.

Meanwhile, separate searches took place in the Republic of Ireland connected to the probe into illegally held IRA funds.

Seven offices in County Louth were searched by officers from the Criminal Assets Bureau.

A quantity of documents were seized during the raids but no arrests were made.

Thomas Murphy lost a libel case against The Sunday Times in 1998, after the newspaper described him as a prominent IRA member.

The authorities on both sides of the border have been investigating him for years.